Veritas-bu

[Veritas-bu] DLT8000's in a SAN: par performance?

2002-04-12 15:52:09
Subject: [Veritas-bu] DLT8000's in a SAN: par performance?
From: RMarkham AT hafeleamericas DOT com (Markham, Richard)
Date: Fri, 12 Apr 2002 15:52:09 -0400
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my wording was wrong.  I'm not using any software compression in any class
just the hardware compression on the tape drive.  According to Mark
Donaldson
NBU reports the actual data sent to the tape drive.  What gets me is the 
number reported is a little less than half the space occupied by the mount
points
I chose for this paritcular backup. This contradicts the possibility that
NBU
reported the amount of 'compressed' data put on tape....


-----Original Message-----
From: Larry Kingery [mailto:larry.kingery AT veritas DOT com]
Sent: Friday, April 12, 2002 3:25 PM
To: Markham, Richard
Subject: Re: [Veritas-bu] DLT8000's in a SAN: par performance?


4.5 MB/s is probably the disk speed.  It's also possible that you're
  losing some by "compressing" compressed data.

If the data is already compressed by some reasonable means, you can
forget all about 80GB/tape, you'll probably get more like 37.

You'll also probably need a larger SIZE_DATA_BUFFERS to get much more
than that out of a Sun.

Markham, Richard writes:
> I wrote 30gb of compressed data to tape over fiber at 
> 4.5mb/s.  These are QUANTUM DLT8000 tape drives and 
> they claim they are able to run 40gb @ 6mb per second 
> and 80gb compressed @ 12gb/s given that since I was 
> running over a dedicated san from a E420R I thought 
> perhaps I should be in the 7-8mb/s range.  Thanks for 
> any input. 
> 
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> <P><FONT SIZE=2>I wrote 30gb of compressed data to tape over fiber
at</FONT>
> <BR><FONT SIZE=2>4.5mb/s.&nbsp; These are QUANTUM DLT8000 tape drives and
</FONT>
> <BR><FONT SIZE=2>they claim they are able to run 40gb @ 6mb per
second</FONT>
> <BR><FONT SIZE=2>and 80gb compressed @ 12gb/s given that since I was
</FONT>
> <BR><FONT SIZE=2>running over a dedicated san from a E420R I thought
</FONT>
> <BR><FONT SIZE=2>perhaps I should be in the 7-8mb/s range.&nbsp; Thanks
for </FONT>
> <BR><FONT SIZE=2>any input.</FONT>
> </P>
> 
> </BODY>
> </HTML>
-- 
Larry Kingery 
  I don't believe anything that can be stated in a single sentence.

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<P><FONT SIZE=2>my wording was wrong.&nbsp; I'm not using any software 
compression in any class</FONT>
<BR><FONT SIZE=2>just the hardware compression on the tape drive.&nbsp; 
According to Mark Donaldson</FONT>
<BR><FONT SIZE=2>NBU reports the actual data sent to the tape drive.&nbsp; What 
gets me is the </FONT>
<BR><FONT SIZE=2>number reported is a little less than half the space occupied 
by the mount points</FONT>
<BR><FONT SIZE=2>I chose for this paritcular backup. This contradicts the 
possibility that NBU</FONT>
<BR><FONT SIZE=2>reported the amount of 'compressed' data put on tape....</FONT>
</P>
<BR>

<P><FONT SIZE=2>-----Original Message-----</FONT>
<BR><FONT SIZE=2>From: Larry Kingery [<A HREF="mailto:larry.kingery AT veritas 
DOT com">mailto:larry.kingery AT veritas DOT com</A>]</FONT>
<BR><FONT SIZE=2>Sent: Friday, April 12, 2002 3:25 PM</FONT>
<BR><FONT SIZE=2>To: Markham, Richard</FONT>
<BR><FONT SIZE=2>Subject: Re: [Veritas-bu] DLT8000's in a SAN: par 
performance?</FONT>
</P>
<BR>

<P><FONT SIZE=2>4.5 MB/s is probably the disk speed.&nbsp; It's also possible 
that you're</FONT>
<BR><FONT SIZE=2>&nbsp; losing some by &quot;compressing&quot; compressed 
data.</FONT>
</P>

<P><FONT SIZE=2>If the data is already compressed by some reasonable means, you 
can</FONT>
<BR><FONT SIZE=2>forget all about 80GB/tape, you'll probably get more like 
37.</FONT>
</P>

<P><FONT SIZE=2>You'll also probably need a larger SIZE_DATA_BUFFERS to get 
much more</FONT>
<BR><FONT SIZE=2>than that out of a Sun.</FONT>
</P>

<P><FONT SIZE=2>Markham, Richard writes:</FONT>
<BR><FONT SIZE=2>&gt; I wrote 30gb of compressed data to tape over fiber at 
</FONT>
<BR><FONT SIZE=2>&gt; 4.5mb/s.&nbsp; These are QUANTUM DLT8000 tape drives and 
</FONT>
<BR><FONT SIZE=2>&gt; they claim they are able to run 40gb @ 6mb per second 
</FONT>
<BR><FONT SIZE=2>&gt; and 80gb compressed @ 12gb/s given that since I was 
</FONT>
<BR><FONT SIZE=2>&gt; running over a dedicated san from a E420R I thought 
</FONT>
<BR><FONT SIZE=2>&gt; perhaps I should be in the 7-8mb/s range.&nbsp; Thanks 
for </FONT>
<BR><FONT SIZE=2>&gt; any input. </FONT>
<BR><FONT SIZE=2>&gt; </FONT>
<BR><FONT SIZE=2>&gt; &lt;!DOCTYPE HTML PUBLIC &quot;-//W3C//DTD HTML 
3.2//EN&quot;&gt;</FONT>
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Exchange Server version 5.5.2650.12&quot;&gt;</FONT>
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performance?&lt;/TITLE&gt;</FONT>
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<BR><FONT SIZE=2>&gt; </FONT>
<BR><FONT SIZE=2>&gt; &lt;P&gt;&lt;FONT SIZE=2&gt;I wrote 30gb of compressed 
data to tape over fiber at&lt;/FONT&gt;</FONT>
<BR><FONT SIZE=2>&gt; &lt;BR&gt;&lt;FONT SIZE=2&gt;4.5mb/s.&amp;nbsp; These are 
QUANTUM DLT8000 tape drives and &lt;/FONT&gt;</FONT>
<BR><FONT SIZE=2>&gt; &lt;BR&gt;&lt;FONT SIZE=2&gt;they claim they are able to 
run 40gb @ 6mb per second&lt;/FONT&gt;</FONT>
<BR><FONT SIZE=2>&gt; &lt;BR&gt;&lt;FONT SIZE=2&gt;and 80gb compressed @ 12gb/s 
given that since I was &lt;/FONT&gt;</FONT>
<BR><FONT SIZE=2>&gt; &lt;BR&gt;&lt;FONT SIZE=2&gt;running over a dedicated san 
from a E420R I thought &lt;/FONT&gt;</FONT>
<BR><FONT SIZE=2>&gt; &lt;BR&gt;&lt;FONT SIZE=2&gt;perhaps I should be in the 
7-8mb/s range.&amp;nbsp; Thanks for &lt;/FONT&gt;</FONT>
<BR><FONT SIZE=2>&gt; &lt;BR&gt;&lt;FONT SIZE=2&gt;any 
input.&lt;/FONT&gt;</FONT>
<BR><FONT SIZE=2>&gt; &lt;/P&gt;</FONT>
<BR><FONT SIZE=2>&gt; </FONT>
<BR><FONT SIZE=2>&gt; &lt;/BODY&gt;</FONT>
<BR><FONT SIZE=2>&gt; &lt;/HTML&gt;</FONT>
<BR><FONT SIZE=2>-- </FONT>
<BR><FONT SIZE=2>Larry Kingery </FONT>
<BR><FONT SIZE=2>&nbsp; I don't believe anything that can be stated in a single 
sentence.</FONT>
</P>

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